If they didn't go rallying you will probably be fine. I have made perfectly good limiting straps with appropriately sized tie down straps (doubled). I think older shocks were more prone to damage if over extended, newer shocks are often the only limiting rear ends have these days. SO for me no rear straps would not be a deal breaker. if you want you can check for drive train damage (this could occur if you went off roading and applied torque at full extension....very unlikely)...pretty quiet on the brickboard these days.... new set of shocks wont set you back much and new shocks are always a nice treat.
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Patrick, '68 220 , '53 GMC 4104, '97 VW Transporter.